Gregory S. Keller

Associate Professor of

Conservation Biology and

Landscape Ecology

Primary Research

The focus of my research is on habitat use, productivity, and survivorship of different organisms, particularly as a result of human alteration of natural habitats. Although my interests have shifted among different habitats, various taxonomic groups, and different emphases, the over-riding theme in my research has been on conservation of organisms, particularly birds, at multiple scales in human-dominated landscapes.

Currently, I am interested in seasonal differences in habitat use by migratory birds. Constraints imposed on birds during the breeding season (such as food provision for offspring) are alleviated during migration and winter, perhaps allowing them to use different habitats. In my research, I focus on the use of Geographic Information Systems (GIS) and foraging behavior to understand differences in habitat use at local and regional scales.

Ongoing Research Projects

How do wintering tropical birds respond to natural openings compared to human disturbance? I have begun a project in Belize elucidating the impacts of natural heterogeneity, in the form of riverine openings and hurricane damage, compared to human-induced disturbance, illustrated by residential development and orange orchards. Several species that breed in New England winter in Belize, and many of these species are exhibiting population declines. The 10 Gordon College students enrolled in the Natural History of Belize winter course are my field assistants, collecting data on foraging behavior of 10 focal species. GIS data will be used to measure landscape-level responses to this habitat heterogeneity.

Which small mammals carry the bacterium responsible for Lyme Disease, and does their distribution differ based on forested habitat? With colleague Justin Topp, my students and I are comparing small mammal populations and tick abundance at natural edge, human-induced edge, residential habitat, and interior-forest habitat. By collecting tissues from small mammals and ticks, we are able to establish the prevalence of the bacterium in different hosts and analyze the difference in prevalence in various habitats. Dr. Topp’s lab is analyzing the material using PCR, and my lab will add a landscape perspective using GIS software. Currently, eight students have been involved in this study.

Rose-breasted Grosbeak, a migratory songbird

(photo by Mike Muthersbaugh)

Mike Muthersbaugh (Gordon undergraduate) processes a live White-footed Mouse, checking it for ticks and taking a tissue sample

How are birds impacted by fragmentation during migration? I am finishing a comparison of songbird communities in regions with different levels of forest fragmentation to add to the growing understanding of this important impact. I am using GIS and foraging behavior to see if communities are influenced by the amount of human disturbance and the proximity to the coast in eastern Massachusetts and New Hampshire.

Black-throated Green Warbler (photo Julian Avery)

Whitney Fenton (former Gordon undergraduate) handles a Blue-winged Warbler, a songbird that breeds in Massachusetts and winters in Belize.

What do migratory woodland songbirds do when there is no woodland during migration? I have completed data collection and analysis and am publishing this study comparing bird communities during different seasons in three habitats (native stands of cottonwood and elm, residential parks, and invasive stands of salt cedar) on the Llano Estacado of New Mexico. This region comprises an area of short-grass prairie with limited (<3%) wooded habitat. I am investigating whether bird behavior can be used as an index to habitat quality by comparing strike rate and success and movement rate of Wilson's warblers, MacGillivray's warblers, and yellow-rumped warblers during spring and fall migration.